JP5165521B2 - Process for producing expanded polyolefin resin particles with excellent mold filling - Google Patents
Process for producing expanded polyolefin resin particles with excellent mold filling Download PDFInfo
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- JP5165521B2 JP5165521B2 JP2008260579A JP2008260579A JP5165521B2 JP 5165521 B2 JP5165521 B2 JP 5165521B2 JP 2008260579 A JP2008260579 A JP 2008260579A JP 2008260579 A JP2008260579 A JP 2008260579A JP 5165521 B2 JP5165521 B2 JP 5165521B2
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- Prior art keywords
- polyolefin resin
- particles
- resin particles
- weight
- expanded
- Prior art date
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- 239000002245 particle Substances 0.000 title claims description 218
- 229920005672 polyolefin resin Polymers 0.000 title claims description 168
- 238000011049 filling Methods 0.000 title description 32
- 238000000034 method Methods 0.000 title description 10
- 230000008569 process Effects 0.000 title description 2
- -1 Glycerin ester Chemical class 0.000 claims description 63
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerol Natural products OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 claims description 57
- 235000011187 glycerol Nutrition 0.000 claims description 41
- 125000004432 carbon atom Chemical group C* 0.000 claims description 40
- 235000014113 dietary fatty acids Nutrition 0.000 claims description 36
- 239000000194 fatty acid Substances 0.000 claims description 36
- 229930195729 fatty acid Natural products 0.000 claims description 36
- 239000006260 foam Substances 0.000 claims description 35
- 239000000126 substance Substances 0.000 claims description 32
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 32
- 150000004665 fatty acids Chemical class 0.000 claims description 31
- 229910001872 inorganic gas Inorganic materials 0.000 claims description 28
- 229920005989 resin Polymers 0.000 claims description 28
- 239000011347 resin Substances 0.000 claims description 28
- 238000004519 manufacturing process Methods 0.000 claims description 25
- 239000004088 foaming agent Substances 0.000 claims description 23
- 239000002612 dispersion medium Substances 0.000 claims description 19
- 239000004743 Polypropylene Substances 0.000 claims description 15
- 229920001155 polypropylene Polymers 0.000 claims description 15
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 14
- 125000002887 hydroxy group Chemical group [H]O* 0.000 claims description 10
- 150000002894 organic compounds Chemical class 0.000 claims description 10
- 229910001873 dinitrogen Inorganic materials 0.000 claims description 9
- 239000002202 Polyethylene glycol Substances 0.000 claims description 5
- 229920001223 polyethylene glycol Polymers 0.000 claims description 5
- 239000003795 chemical substances by application Substances 0.000 claims description 3
- QIQXTHQIDYTFRH-UHFFFAOYSA-N octadecanoic acid Chemical compound CCCCCCCCCCCCCCCCCC(O)=O QIQXTHQIDYTFRH-UHFFFAOYSA-N 0.000 claims description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 26
- 238000005187 foaming Methods 0.000 description 24
- 238000002844 melting Methods 0.000 description 20
- 230000008018 melting Effects 0.000 description 20
- 238000010438 heat treatment Methods 0.000 description 15
- 238000010097 foam moulding Methods 0.000 description 14
- 239000001569 carbon dioxide Substances 0.000 description 13
- 229910002092 carbon dioxide Inorganic materials 0.000 description 13
- 239000002270 dispersing agent Substances 0.000 description 13
- 239000006185 dispersion Substances 0.000 description 9
- 239000003381 stabilizer Substances 0.000 description 9
- 239000004711 α-olefin Substances 0.000 description 9
- TZCXTZWJZNENPQ-UHFFFAOYSA-L barium sulfate Chemical compound [Ba+2].[O-]S([O-])(=O)=O TZCXTZWJZNENPQ-UHFFFAOYSA-L 0.000 description 8
- 239000000155 melt Substances 0.000 description 8
- 238000000465 moulding Methods 0.000 description 8
- 239000002667 nucleating agent Substances 0.000 description 8
- 238000005192 partition Methods 0.000 description 8
- 238000011156 evaluation Methods 0.000 description 7
- 239000007789 gas Substances 0.000 description 7
- 239000012860 organic pigment Substances 0.000 description 7
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 6
- 229920000098 polyolefin Polymers 0.000 description 6
- 239000000454 talc Substances 0.000 description 6
- 229910052623 talc Inorganic materials 0.000 description 6
- DNIAPMSPPWPWGF-GSVOUGTGSA-N (R)-(-)-Propylene glycol Chemical compound C[C@@H](O)CO DNIAPMSPPWPWGF-GSVOUGTGSA-N 0.000 description 5
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 5
- 239000000654 additive Substances 0.000 description 5
- 229910052783 alkali metal Inorganic materials 0.000 description 5
- 239000013078 crystal Substances 0.000 description 5
- 238000001938 differential scanning calorimetry curve Methods 0.000 description 5
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- 229920000642 polymer Polymers 0.000 description 5
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- 239000005995 Aluminium silicate Substances 0.000 description 4
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 4
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 4
- 239000005977 Ethylene Substances 0.000 description 4
- 239000004793 Polystyrene Substances 0.000 description 4
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 4
- 150000008052 alkyl sulfonates Chemical class 0.000 description 4
- 235000012211 aluminium silicate Nutrition 0.000 description 4
- ZFSLODLOARCGLH-UHFFFAOYSA-N isocyanuric acid Chemical compound OC1=NC(O)=NC(O)=N1 ZFSLODLOARCGLH-UHFFFAOYSA-N 0.000 description 4
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 description 4
- 239000005022 packaging material Substances 0.000 description 4
- 229920002223 polystyrene Polymers 0.000 description 4
- QORWJWZARLRLPR-UHFFFAOYSA-H tricalcium bis(phosphate) Chemical compound [Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O QORWJWZARLRLPR-UHFFFAOYSA-H 0.000 description 4
- 235000019731 tricalcium phosphate Nutrition 0.000 description 4
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 3
- NRCMAYZCPIVABH-UHFFFAOYSA-N Quinacridone Chemical compound N1C2=CC=CC=C2C(=O)C2=C1C=C1C(=O)C3=CC=CC=C3NC1=C2 NRCMAYZCPIVABH-UHFFFAOYSA-N 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 229920001400 block copolymer Polymers 0.000 description 3
- 239000001506 calcium phosphate Substances 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 229920001577 copolymer Polymers 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000005227 gel permeation chromatography Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000002609 medium Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 229920000570 polyether Polymers 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- 229920005992 thermoplastic resin Polymers 0.000 description 3
- 229910000391 tricalcium phosphate Inorganic materials 0.000 description 3
- 229940078499 tricalcium phosphate Drugs 0.000 description 3
- RFFLAFLAYFXFSW-UHFFFAOYSA-N 1,2-dichlorobenzene Chemical compound ClC1=CC=CC=C1Cl RFFLAFLAYFXFSW-UHFFFAOYSA-N 0.000 description 2
- VBICKXHEKHSIBG-UHFFFAOYSA-N 1-monostearoylglycerol Chemical compound CCCCCCCCCCCCCCCCCC(=O)OCC(O)CO VBICKXHEKHSIBG-UHFFFAOYSA-N 0.000 description 2
- 229920002126 Acrylic acid copolymer Polymers 0.000 description 2
- KAKZBPTYRLMSJV-UHFFFAOYSA-N Butadiene Chemical class C=CC=C KAKZBPTYRLMSJV-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- LCGLNKUTAGEVQW-UHFFFAOYSA-N Dimethyl ether Chemical compound COC LCGLNKUTAGEVQW-UHFFFAOYSA-N 0.000 description 2
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 description 2
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 description 2
- 229920000877 Melamine resin Polymers 0.000 description 2
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 description 2
- OFBQJSOFQDEBGM-UHFFFAOYSA-N Pentane Chemical compound CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 125000000217 alkyl group Chemical group 0.000 description 2
- 229940045714 alkyl sulfonate alkylating agent Drugs 0.000 description 2
- 239000003945 anionic surfactant Substances 0.000 description 2
- 150000001491 aromatic compounds Chemical class 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 229910021538 borax Inorganic materials 0.000 description 2
- 230000003139 buffering effect Effects 0.000 description 2
- 229910000019 calcium carbonate Inorganic materials 0.000 description 2
- 238000000113 differential scanning calorimetry Methods 0.000 description 2
- 150000002148 esters Chemical class 0.000 description 2
- 230000001747 exhibiting effect Effects 0.000 description 2
- 239000003063 flame retardant Substances 0.000 description 2
- 150000002314 glycerols Chemical class 0.000 description 2
- 229920001519 homopolymer Polymers 0.000 description 2
- 239000011810 insulating material Substances 0.000 description 2
- NNPPMTNAJDCUHE-UHFFFAOYSA-N isobutane Chemical compound CC(C)C NNPPMTNAJDCUHE-UHFFFAOYSA-N 0.000 description 2
- 229920000092 linear low density polyethylene Polymers 0.000 description 2
- 239000004707 linear low-density polyethylene Substances 0.000 description 2
- GVALZJMUIHGIMD-UHFFFAOYSA-H magnesium phosphate Chemical compound [Mg+2].[Mg+2].[Mg+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O GVALZJMUIHGIMD-UHFFFAOYSA-H 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical compound NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 239000012188 paraffin wax Substances 0.000 description 2
- 125000002080 perylenyl group Chemical group C1(=CC=C2C=CC=C3C4=CC=CC5=CC=CC(C1=C23)=C45)* 0.000 description 2
- CSHWQDPOILHKBI-UHFFFAOYSA-N peryrene Natural products C1=CC(C2=CC=CC=3C2=C2C=CC=3)=C3C2=CC=CC3=C1 CSHWQDPOILHKBI-UHFFFAOYSA-N 0.000 description 2
- 230000000704 physical effect Effects 0.000 description 2
- 239000004328 sodium tetraborate Substances 0.000 description 2
- 235000010339 sodium tetraborate Nutrition 0.000 description 2
- BDHFUVZGWQCTTF-UHFFFAOYSA-M sulfonate Chemical compound [O-]S(=O)=O BDHFUVZGWQCTTF-UHFFFAOYSA-M 0.000 description 2
- 239000002344 surface layer Substances 0.000 description 2
- 239000004094 surface-active agent Substances 0.000 description 2
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 2
- 238000011282 treatment Methods 0.000 description 2
- BIKXLKXABVUSMH-UHFFFAOYSA-N trizinc;diborate Chemical compound [Zn+2].[Zn+2].[Zn+2].[O-]B([O-])[O-].[O-]B([O-])[O-] BIKXLKXABVUSMH-UHFFFAOYSA-N 0.000 description 2
- RNFJDJUURJAICM-UHFFFAOYSA-N 2,2,4,4,6,6-hexaphenoxy-1,3,5-triaza-2$l^{5},4$l^{5},6$l^{5}-triphosphacyclohexa-1,3,5-triene Chemical compound N=1P(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP=1(OC=1C=CC=CC=1)OC1=CC=CC=C1 RNFJDJUURJAICM-UHFFFAOYSA-N 0.000 description 1
- ATVJXMYDOSMEPO-UHFFFAOYSA-N 3-prop-2-enoxyprop-1-ene Chemical compound C=CCOCC=C ATVJXMYDOSMEPO-UHFFFAOYSA-N 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 description 1
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 1
- 229920002845 Poly(methacrylic acid) Polymers 0.000 description 1
- OFOBLEOULBTSOW-UHFFFAOYSA-N Propanedioic acid Natural products OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 description 1
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 1
- ULUAUXLGCMPNKK-UHFFFAOYSA-N Sulfobutanedioic acid Chemical class OC(=O)CC(C(O)=O)S(O)(=O)=O ULUAUXLGCMPNKK-UHFFFAOYSA-N 0.000 description 1
- 239000011954 Ziegler–Natta catalyst Substances 0.000 description 1
- 239000006096 absorbing agent Substances 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000003570 air Substances 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 150000004996 alkyl benzenes Chemical class 0.000 description 1
- 150000008051 alkyl sulfates Chemical class 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
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- 150000001412 amines Chemical class 0.000 description 1
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- 239000003963 antioxidant agent Substances 0.000 description 1
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- 239000002585 base Substances 0.000 description 1
- 239000000440 bentonite Substances 0.000 description 1
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- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 description 1
- WPYMKLBDIGXBTP-UHFFFAOYSA-N benzoic acid Chemical compound OC(=O)C1=CC=CC=C1 WPYMKLBDIGXBTP-UHFFFAOYSA-N 0.000 description 1
- QRUDEWIWKLJBPS-UHFFFAOYSA-N benzotriazole Chemical compound C1=CC=C2N[N][N]C2=C1 QRUDEWIWKLJBPS-UHFFFAOYSA-N 0.000 description 1
- 239000012964 benzotriazole Substances 0.000 description 1
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- 150000001642 boronic acid derivatives Chemical class 0.000 description 1
- 239000001110 calcium chloride Substances 0.000 description 1
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- 150000007942 carboxylates Chemical class 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
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- 150000005690 diesters Chemical class 0.000 description 1
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- SVUQHVRAGMNPLW-UHFFFAOYSA-N glycerol monostearate Natural products CCCCCCCCCCCCCCCCC(=O)OCC(O)CO SVUQHVRAGMNPLW-UHFFFAOYSA-N 0.000 description 1
- 125000003976 glyceryl group Chemical group [H]C([*])([H])C(O[H])([H])C(O[H])([H])[H] 0.000 description 1
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- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 description 1
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Description
本発明はポリオレフィン系樹脂発泡粒子の製造方法に関する。さらに詳しくは、良好な金型充填性を有する、型内発泡成形体に好適に使用しうるポリオレフィン系樹脂発泡粒子の製造方法に関する。 The present invention relates to a method for producing polyolefin resin expanded particles. More specifically, the present invention relates to a method for producing polyolefin-based resin foamed particles having good mold filling properties and suitable for use in an in-mold foam molded article.
ポリオレフィン系樹脂発泡体は緩衝性、断熱性等の物性に優れることから、包装材、緩衝材、断熱材、建築部材など様々な用途に使用されている。特にポリオレフィン系樹脂発泡粒子を金型に充填し、水蒸気などで加熱して発泡粒子同士を融着せしめて所定形状の発泡体を得る型内発泡成形法は、複雑な形状の製品を比較的容易に得ることができるため、多くの用途に用いられている。 Polyolefin resin foams are excellent in physical properties such as buffering properties and heat insulating properties, and are therefore used in various applications such as packaging materials, buffer materials, heat insulating materials, and building members. In particular, the in-mold foam molding method that fills polyolefin resin foam particles in a mold and heats them with steam to fuse the foam particles together to obtain a foam with a predetermined shape is relatively easy for products with complex shapes. Therefore, it is used for many purposes.
型内発泡成形に使用するポリオレフィン系樹脂発泡粒子は、例えば、耐圧容器内にポリオレフィン系樹脂粒子を水系分散媒に分散剤を用いて分散させ、ポリオレフィン系樹脂粒子の軟化温度以上の温度まで加熱、加圧した後、耐圧容器の内圧よりも低い圧力域に放出することにより製造することができる。 Polyolefin resin foam particles used for in-mold foam molding are, for example, dispersing polyolefin resin particles in a pressure-resistant container using a dispersant in an aqueous dispersion medium, and heating to a temperature equal to or higher than the softening temperature of the polyolefin resin particles. After pressurization, it can be produced by discharging it to a pressure range lower than the internal pressure of the pressure vessel.
ポリオレフィン系樹脂型内発泡成形体のなかでも、包装材や緩衝材に使用される型内発泡成形体は緩衝性能を付与するため通常、30倍以上の高発泡倍率である。このため、型内発泡成形に使用するポリオレフィン系樹脂発泡粒子も20倍以上の高発泡倍率であることが求められる。 Among the polyolefin-based in-mold foam molded articles, the in-mold foam molded articles used for packaging materials and cushioning materials usually have a high expansion ratio of 30 times or more in order to provide buffer performance. For this reason, the polyolefin resin expanded particles used for in-mold foam molding are also required to have a high expansion ratio of 20 times or more.
特許文献1や特許文献2には硼酸塩化合物が添加されたポリオレフィン系樹脂を用いることにより発泡しにくい無機ガスを発泡剤として使用しても高発泡倍率のポリオレフィン系樹脂発泡粒子が得られることが記載されている。
しかしながら、高発泡倍率の発泡粒子は通常粒子径が大きい。このため型内発泡成形において金型が薄肉部分や複雑な形状を有していると、大きい粒子径の発泡粒子を金型に十分充填することが困難になる場合がある。 However, expanded particles with a high expansion ratio usually have a large particle size. For this reason, if the mold has a thin portion or a complicated shape in the in-mold foam molding, it may be difficult to sufficiently fill the mold with foam particles having a large particle diameter.
特許文献3にはポリプロピレン系樹脂発泡粒子を製造する際の分散剤量や加熱温度を調整することにより、金型への充填性に優れた発泡粒子を得ることができることが開示されている。また、特許文献4には円柱状あるいは楕円柱状であり、特定の特性を有する発泡粒子が金型への充填性に優れることが開示されている。 Patent Document 3 discloses that foam particles having excellent filling properties in a mold can be obtained by adjusting the amount of dispersant and heating temperature when producing polypropylene resin foam particles. Further, Patent Document 4 discloses that foamed particles having a columnar shape or an elliptical column shape and having specific characteristics are excellent in filling property into a mold.
特許文献5には高級脂肪酸グリセリンエステルと極性基を有する芳香族化合物が添加されたポリスチレン等の発泡性熱可塑性樹脂粒子は発泡に際し粒子同士がブロッキングしにくく、その結果金型充填性に優れることが開示されている。
本発明の目的は、高発泡倍率であり且つ金型充填性に優れたポリオレフィン系樹脂発泡粒子の製造方法を提供することである。 An object of the present invention is to provide a method for producing expanded polyolefin resin particles having a high expansion ratio and excellent mold filling property.
本発明者は親水性物質と共に炭素数6以上30以下の脂肪酸のグリセリンエステルを添加したポリオレフィン系樹脂粒子を使用することにより、高発泡倍率であって金型充填性に優れたポリオレフィン系樹脂発泡粒子を製造できることを見いだした。 The present inventor uses a polyolefin-based resin particle to which a glycerin ester of a fatty acid having 6 to 30 carbon atoms is added together with a hydrophilic substance, so that the polyolefin-based resin expanded particle having a high expansion ratio and excellent mold filling property It was found that can be manufactured.
すなわち、本発明は、耐圧容器内にポリオレフィン系樹脂粒子を水系分散媒に分散させ、無機ガスを添加し、ポリオレフィン系樹脂粒子の軟化温度以上の温度まで加熱、加圧してポリオレフィン系樹脂粒子に発泡剤を含浸させ、発泡剤が含浸されたポリオレフィン系樹脂粒子を耐圧容器の内圧よりも低い圧力域に放出する工程を含む、発泡倍率20倍以上のポリオレフィン系樹脂発泡粒子の製造方法であって、ポリオレフィン系樹脂粒子が次の(A)成分及び(B)成分を含有することを特徴とするポリオレフィン系樹脂発泡粒子の製造方法に関する。
(A)炭素数6以上30以下の脂肪酸のグリセリンエステル
(B)無機ガスとして窒素ガスを使用して発泡粒子を製造した場合、発泡粒子の含水率を0.7重量%以上にする、分子量が600以下の親水性物質
That is, in the present invention, polyolefin resin particles are dispersed in an aqueous dispersion medium in a pressure vessel, an inorganic gas is added, and heated to a temperature equal to or higher than the softening temperature of the polyolefin resin particles to be foamed into the polyolefin resin particles. A method for producing polyolefin resin foamed particles having an expansion ratio of 20 times or more, comprising a step of impregnating an agent and releasing the polyolefin resin particles impregnated with the foaming agent into a pressure region lower than the internal pressure of the pressure vessel, The present invention relates to a method for producing expanded polyolefin resin particles, wherein the polyolefin resin particles contain the following components (A) and (B).
(A) Glycerin ester of fatty acid having 6 to 30 carbon atoms (B) When foamed particles are produced using nitrogen gas as an inorganic gas, the water content of the foamed particles is 0.7% by weight or more. 600 or less hydrophilic substance
好ましい態様としては、
(1)炭素数6以上30以下の脂肪酸のグリセリンエステルが、炭素数10以上24以下の脂肪酸のグリセリンエステルである、
(2)炭素数10以上24以下の脂肪酸のグリセリンエステルが、炭素数10以上24以下の脂肪酸のグリセリンモノエステルを主成分とする、
(3)炭素数10以上24以下の脂肪酸のグリセリンモノエステルが、ステアリン酸グリセリンモノエステルである、
(4)(B)成分が、分子量600以下の親水性物質が、水酸基含有有機化合物及び/又は硼酸塩化合物である、
(5)(B)成分が、分子量600以下の水酸基含有有機化合物である、
(6)分子量600以下の水酸基含有有機化合物が、分子量600以下のポリエチレングリコールである、
(7)分子量600以下の水酸基含有有機化合物が、グリセリンである、
(8)ポリオレフィン系樹脂が、ポリプロピレン系樹脂である、
前記記載のポリオレフィン系樹脂発泡粒子の製造方法に関する。
As a preferred embodiment,
(1) The glycerol ester of a fatty acid having 6 to 30 carbon atoms is a glycerol ester of a fatty acid having 10 to 24 carbon atoms.
(2) The glycerin ester of a fatty acid having 10 to 24 carbon atoms is mainly composed of a glycerin monoester of a fatty acid having 10 to 24 carbon atoms,
(3) The glycerin monoester of a fatty acid having 10 to 24 carbon atoms is a glyceryl monoester stearate,
(4) The component (B) is a hydrophilic substance having a molecular weight of 600 or less, which is a hydroxyl group-containing organic compound and / or a borate compound.
(5) The component (B) is a hydroxyl group-containing organic compound having a molecular weight of 600 or less.
(6) The hydroxyl group-containing organic compound having a molecular weight of 600 or less is polyethylene glycol having a molecular weight of 600 or less.
(7) The hydroxyl group-containing organic compound having a molecular weight of 600 or less is glycerin.
(8) The polyolefin resin is a polypropylene resin.
The present invention relates to a method for producing the polyolefin resin expanded particles described above.
本発明の製造方法によれば、高発泡倍率であり且つ金型充填性に優れたポリオレフィン系樹脂発泡粒子を簡便な方法により製造することができる。 According to the production method of the present invention, it is possible to produce polyolefin resin expanded particles having a high expansion ratio and excellent mold filling property by a simple method.
本発明で用いられるポリオレフィン系樹脂粒子は、ポリオレフィン系樹脂から製造される。ポリオレフィン系樹脂の例としては、ポリプロピレン系樹脂やポリエチレン系樹脂などが挙げられる。 The polyolefin resin particles used in the present invention are produced from a polyolefin resin. Examples of polyolefin resins include polypropylene resins and polyethylene resins.
ポリプロピレン系樹脂としては、プロピレンホモポリマー、プロピレン−α−オレフィンランダム共重合体、プロピレン−α−オレフィンブロック共重合体などが挙げられる。ここでいうα−オレフィンとしては、炭素数2あるいは4〜15のα−オレフィンなどが挙げられ、これらは、単独で用いてもよく、2種以上併用してもよい。これらのポリプロピレン系樹脂中でも、プロピレン−エチレンランダム共重合体、プロピレン−エチレン−ブテン−1ランダム共重合体、プロピレン−ブテン−1ランダム共重合体であって、プロピレン以外のコモノマー含量が1〜5重量%であるポリプロピレン系樹脂が良好な発泡性を示し、好適に使用し得る。また共重合体ポリマーでは、ホモポリマーに比較して、水や二酸化炭素等の発泡剤が含浸し易い特性も有しており、好適である。 Examples of the polypropylene resin include a propylene homopolymer, a propylene-α-olefin random copolymer, and a propylene-α-olefin block copolymer. Examples of the α-olefin herein include α-olefins having 2 or 4 to 15 carbon atoms, and these may be used alone or in combination of two or more. Among these polypropylene resins, propylene-ethylene random copolymer, propylene-ethylene-butene-1 random copolymer, propylene-butene-1 random copolymer, and a comonomer content other than propylene is 1 to 5 wt. % Polypropylene-based resin exhibits good foaming properties and can be suitably used. In addition, the copolymer polymer is suitable because it has a characteristic that it can be easily impregnated with a foaming agent such as water or carbon dioxide as compared with a homopolymer.
ポリプロピレン系樹脂を用いる場合、融点は130℃以上165℃以下であることが好ましく、更には135℃以上155℃以下であることが好ましい。融点が130℃以上165℃以下であると、発泡性、成形性に優れ、ポリオレフィン系樹脂型内発泡成形体としたときの機械的強度、耐熱性に優れた発泡粒子を得ることが出来る傾向がある。ここで、融点とは、示差走査熱量計によって試料1〜10mgを40℃から220℃まで10℃/分の速度で昇温し、その後40℃まで10℃/分の速度で冷却し結晶化させた後、再度220℃まで10℃/分の速度で昇温した時に得られるDSC曲線における吸熱ピークのピーク温度をいう。 When a polypropylene resin is used, the melting point is preferably 130 ° C. or higher and 165 ° C. or lower, and more preferably 135 ° C. or higher and 155 ° C. or lower. When the melting point is 130 ° C. or higher and 165 ° C. or lower, the foamed particles are excellent in foamability and moldability, and there is a tendency that foamed particles having excellent mechanical strength and heat resistance when made into a polyolefin resin in-mold foam-molded product can be obtained. is there. Here, the melting point means that 1-10 mg of a sample is heated from 40 ° C. to 220 ° C. at a rate of 10 ° C./min by a differential scanning calorimeter, and then cooled to 40 ° C. at a rate of 10 ° C./min to be crystallized. Then, the peak temperature of the endothermic peak in the DSC curve obtained when the temperature is increased again to 220 ° C. at a rate of 10 ° C./min.
更に、ポリプロピレン系樹脂のメルトインデックス(MI)は、2g/10分以上11g/10分以下が好ましく、より好ましくは3g/10分以上10g/10分以下であり、最も好ましくは4g/10分以上8g/10分以下である。メルトインデックスが2g/10分未満では、高発泡倍率の発泡粒子が得られにくくなるとともに、気泡も不均一になる傾向がある。また、メルトインデックスが11g/10分を超えた場合、高発泡倍率の発泡粒子は得やすくなるが、発泡粒子内の気泡が破泡し易く、発泡粒子の連泡率が高くなる傾向にあるとともに、気泡も不均一になる傾向がある。なお、ポリプロピレン系樹脂のメルトインデックスは、JIS K7210に準拠し、温度230℃、荷重2.16kgで測定した値である。 Furthermore, the melt index (MI) of the polypropylene resin is preferably 2 g / 10 min or more and 11 g / 10 min or less, more preferably 3 g / 10 min or more and 10 g / 10 min or less, and most preferably 4 g / 10 min or more. It is 8 g / 10 minutes or less. When the melt index is less than 2 g / 10 minutes, it becomes difficult to obtain expanded particles having a high expansion ratio, and the bubbles tend to be non-uniform. Further, when the melt index exceeds 11 g / 10 min, it becomes easy to obtain expanded particles with a high expansion ratio, but the bubbles in the expanded particles tend to break and the open cell rate of the expanded particles tends to increase. , Bubbles also tend to be non-uniform. The melt index of the polypropylene resin is a value measured at a temperature of 230 ° C. and a load of 2.16 kg in accordance with JIS K7210.
ポリプロピレン系樹脂の重量平均分子量(以下、Mwと表記する場合がある)と数平均分子量(以下、Mnと表記する場合がある)の比(Mw/Mn)は6.0以下が好ましい。Mw/Mnは5以下がより好ましい。Mw/Mnが6.0を越える場合、本発明の製造方法によって得られたポリオレフィン系樹脂発泡粒子を型内発泡成形して得られる、ポリオレフィン系樹脂型内発泡成形体の表面性や収縮性が悪化する傾向にある。大きい発泡倍率を有するポリオレフィン系樹脂型内発泡成形体は単位体積当たりの樹脂量が少ないため、剛性がなく、金型寸法に対する収縮率が大きい傾向がある。従って、本発明においてはMw/Mnができるだけ小さい樹脂を使用することが好ましい。 The ratio (Mw / Mn) of the weight average molecular weight (hereinafter sometimes referred to as Mw) and the number average molecular weight (hereinafter sometimes referred to as Mn) of the polypropylene resin is preferably 6.0 or less. Mw / Mn is more preferably 5 or less. When Mw / Mn exceeds 6.0, the surface property and shrinkage of the polyolefin resin in-mold foam molded product obtained by in-mold foam molding of the polyolefin resin foam particles obtained by the production method of the present invention. It tends to get worse. A polyolefin-based resin-molded foam-molded article having a large expansion ratio has a small amount of resin per unit volume, and therefore has no rigidity and tends to have a large shrinkage ratio with respect to the mold dimensions. Therefore, in the present invention, it is preferable to use a resin having as low Mw / Mn as possible.
Mn及びMwは以下の条件において測定される。
測定機器 :Waters社製Alliance GPC 2000型 ゲルパーミエーションクロマトグラフィー(GPC)
カラム :TSKgel GMH6−HT 2本、
TSKgel GMH6−HTL 2本(それぞれ、内径7.5mm×長さ300mm、東ソー社製)
移動相 :o−ジクロロベンゼン(0.025%BHT含有)
カラム温度:140℃
流速 :1.0mL/min
試料濃度 :0.15%(W/V)−o−ジクロロベンゼン
注入量 :500μL
分子量較正:ポリスチレン換算(標準ポリスチレンによる較正)
Mn and Mw are measured under the following conditions.
Measuring instrument: Alliance GPC 2000 type gel permeation chromatography (GPC) manufactured by Waters
Column: 2 TSKgel GMH6-HT,
Two TSKgel GMH6-HTL (each inner diameter 7.5mm x length 300mm, manufactured by Tosoh Corporation)
Mobile phase: o-dichlorobenzene (containing 0.025% BHT)
Column temperature: 140 ° C
Flow rate: 1.0 mL / min
Sample concentration: 0.15% (W / V) -o-dichlorobenzene injection amount: 500 μL
Molecular weight calibration: Polystyrene conversion (calibration with standard polystyrene)
ポリエチレン系樹脂としては、エチレンホモポリマー、エチレン−α−オレフィンランダム共重合体、エチレン−α−オレフィンブロック共重合体、低密度ポリエチレン、高密度ポリエチレン、直鎖状低密度ポリエチレンなどが挙げられる。ここで言う、α−オレフィンとしては、炭素数3〜15のα−オレフィンなどが挙げられ、これらは、単独で用いてもよく、2種以上併用してもよい。これらのポリエチレン系樹脂の中でも、エチレン−α−オレフィンブロック共重合体であってエチレン以外のコモノマー含量が1〜10重量%である場合、あるいは直鎖状低密度ポリエチレンである場合に良好な発泡性を示し、好適に使用し得る。 Examples of the polyethylene resin include ethylene homopolymer, ethylene-α-olefin random copolymer, ethylene-α-olefin block copolymer, low density polyethylene, high density polyethylene, and linear low density polyethylene. The α-olefin referred to herein includes α-olefins having 3 to 15 carbon atoms, and these may be used alone or in combination of two or more. Among these polyethylene-based resins, good foamability when ethylene-α-olefin block copolymer has a comonomer content other than ethylene of 1 to 10% by weight or is a linear low density polyethylene And can be suitably used.
ポリエチレン系樹脂を用いる場合、融点は、110℃以上140℃以下であることが好ましく、更には120℃以上130℃以下であることが、発泡性、成形性に優れ、ポリオレフィン系樹脂型内発泡成形体としたときの機械的強度、耐熱性に優れた発泡粒子を得ることが出来る傾向があるため、好ましい。更に、ポリエチレン系樹脂のメルトインデックスは、0.5g/10分以上30g/10分以下であることが好ましく、より好ましくは1g/10分以上5g/10分以下であり、最も好ましくは1.5g/10分以上2.5g/10分以下である。メルトインデックスが0.5g/10分未満では、高発泡倍率の発泡粒子が得られにくくなるとともに、気泡も不均一になる傾向がある。また、メルトインデックスが30g/10分を超えた場合、発泡しやすいものの、気泡が破泡し易く、発泡粒子の連泡率が高くなる傾向にあるとともに、気泡も不均一になる傾向がある。なお、ポリエチレン系樹脂のメルトインデックスは、JIS K7210に準拠し、温度190℃、荷重2.16kgで測定した値である。 When a polyethylene resin is used, the melting point is preferably 110 ° C. or more and 140 ° C. or less, and further 120 ° C. or more and 130 ° C. or less is excellent in foamability and moldability, and polyolefin resin-in-mold foam molding. Since there exists a tendency which can obtain the expanded particle excellent in the mechanical strength and heat resistance when it is set as a body, it is preferable. Further, the melt index of the polyethylene resin is preferably 0.5 g / 10 min or more and 30 g / 10 min or less, more preferably 1 g / 10 min or more and 5 g / 10 min or less, and most preferably 1.5 g. / 10 minutes or more and 2.5 g / 10 minutes or less. When the melt index is less than 0.5 g / 10 min, it becomes difficult to obtain expanded particles with a high expansion ratio, and the bubbles tend to be non-uniform. In addition, when the melt index exceeds 30 g / 10 min, although it is easy to foam, the bubbles are liable to break, the open-cell ratio of the foamed particles tends to increase, and the bubbles also tend to be non-uniform. The melt index of the polyethylene resin is a value measured at a temperature of 190 ° C. and a load of 2.16 kg in accordance with JIS K7210.
本発明において使用するポリオレフィン系樹脂を製造する際に用いられる触媒としては特に制限はなく、例えば、Ziegler−Natta触媒、メタロセン触媒などが挙げられる。以上、ポリオレフィン系樹脂について説明したが、これらポリオレフィン系樹脂は単独で用いてもよく、2種以上を混合するなどして用いても構わない。本発明の効果がより顕著に発揮されるため、ポリオレフィン系樹脂としてポリプロピレン系樹脂を使用することが好ましい。 There is no restriction | limiting in particular as a catalyst used when manufacturing polyolefin resin used in this invention, For example, a Ziegler-Natta catalyst, a metallocene catalyst, etc. are mentioned. The polyolefin resin has been described above, but these polyolefin resins may be used alone or in combination of two or more. Since the effects of the present invention are more remarkably exhibited, it is preferable to use a polypropylene resin as the polyolefin resin.
本発明の製造方法においては、ポリオレフィン系樹脂粒子が、(A)炭素数6以上30以下の脂肪酸のグリセリンエステルを含む。本発明において、炭素数6以上30以下の脂肪酸のグリセリンエステルは、得られるポリオレフィン系樹脂発泡粒子の金型充填性を向上される作用を有している。ポリオレフィン系樹脂粒子が炭素数6以上30以下の脂肪酸のグリセリンエステルの例としては、化1で表されるグリセリンのモノエステルやジエステルが挙げられる。
In the production method of the present invention, the polyolefin resin particles contain (A) a glycerin ester of a fatty acid having 6 to 30 carbon atoms. In the present invention, a glycerin ester of a fatty acid having 6 to 30 carbon atoms has an effect of improving the mold filling property of the obtained polyolefin resin expanded particles. Examples of the glycerin ester of a fatty acid having a polyolefin resin particle having 6 to 30 carbon atoms include glycerin monoester and diester represented by
本発明で使用する炭素数6以上30以下の脂肪酸のグリセリンエステルの炭素数が少ない場合は分子量が低いため融点が低くなり加工時の取り扱いに注意を要する傾向がある。一般には炭素数18前後のものが自然界に多数存在するため安価であり、よく用いられる。 When the glycerin ester of a fatty acid having 6 to 30 carbon atoms used in the present invention has a small number of carbon atoms, the molecular weight is low, so the melting point is low and the handling during processing tends to require attention. In general, there are many carbon atoms having about 18 carbon atoms in nature, so they are inexpensive and often used.
炭素数6以上30以下の脂肪酸のグリセリンエステルの中でも、炭素数が10以上24以下の脂肪酸のグリセリンエステルであることが好ましく、更には、炭素数10以上24以下の脂肪酸のグリセリンモノエステルを主成分とすることが好ましく、特には、ステアリン酸グリセリンモノエステルであることが好ましい。なお、「主成分とする」とは、50重量%を超えて含むことを意味する。本発明において1種の炭素数6以上30以下の脂肪酸のグリセリンエステルを用いてもよいし、2種以上の炭素数6以上30以下の脂肪酸のグリセリンエステルの混合物を使用してもよい。 Among the glycerin esters of fatty acids having 6 to 30 carbon atoms, glycerin esters of fatty acids having 10 to 24 carbon atoms are preferable, and glycerin monoesters of fatty acids having 10 to 24 carbon atoms are the main components. In particular, glycerol monostearate is preferable. “Containing as a main component” means containing more than 50% by weight. In the present invention, one kind of glycerin ester of a fatty acid having 6 to 30 carbon atoms may be used, or a mixture of two or more kinds of glycerin ester of a fatty acid having 6 to 30 carbon atoms may be used.
炭素数6以上30以下の脂肪酸のグリセリンエステルは、ポリオレフィン系樹脂100重量部に対し、好ましくは0.1重量部以上5重量部以下含まれ、より好ましくは0.1重量部以上3重量部以下含まれる。前記炭素数6以上30以下の脂肪酸のグリセリンエステルの添加量が0.1重量部未満の場合、ポリオレフィン系樹脂発泡粒子の金型充填性が不十分な場合がある。一方、5重量部をこえると型内発泡成形に用いる際、ポリオレフィン系樹脂発泡粒子間の融着性が悪化する場合がある。 The glycerin ester of a fatty acid having 6 to 30 carbon atoms is preferably contained in an amount of 0.1 to 5 parts by weight, more preferably 0.1 to 3 parts by weight, based on 100 parts by weight of the polyolefin resin. included. When the addition amount of the glycerin ester of a fatty acid having 6 to 30 carbon atoms is less than 0.1 parts by weight, the mold filling property of the polyolefin resin expanded particles may be insufficient. On the other hand, when the amount exceeds 5 parts by weight, the fusing property between the polyolefin resin foam particles may deteriorate when used for in-mold foam molding.
特開平6−32934号公報には、高級脂肪酸グリセリンエステルと極性基を有する芳香族化合物が添加されたポリスチレン等の発泡性熱可塑性樹脂粒子は予備発泡に際し、予備発泡粒子同士がブロッキングしにくく、ブロッキングした予備発泡粒子がないために、金型充填性に優れることが開示されている。しかし、本発明の発泡粒子は発泡時ブロッキングすることがない場合においても、炭素数6以上30以下の脂肪酸グリセリンエステルの添加により金型充填性が改善される。従って、本発明のポリオレフィン系樹脂発泡粒子と特開平6−32934号公報記載の発泡性熱可塑性樹脂粒子とは、炭素数6以上30以下の脂肪酸グリセリンエステルの添加により異なる理由によって金型充填性が改善されていると考えられる。詳細な理由は明らかではないが、本発明においては炭素数6以上30以下の脂肪酸グリセリンエステルの帯電防止機能によって金型充填性が改善されていることが推察される。 JP-A-6-32934 discloses that foamed thermoplastic resin particles such as polystyrene to which a higher fatty acid glycerin ester and an aromatic compound having a polar group are added are pre-foamed, and the pre-foamed particles are difficult to block each other. It is disclosed that since there are no pre-expanded particles, the mold filling property is excellent. However, even when the foamed particles of the present invention do not block during foaming, the mold filling property is improved by the addition of a fatty acid glycerin ester having 6 to 30 carbon atoms. Therefore, the polyolefin resin expanded particles of the present invention and the expandable thermoplastic resin particles described in JP-A-6-32934 have different mold filling properties due to different reasons depending on the addition of a fatty acid glycerin ester having 6 to 30 carbon atoms. It is thought that it has improved. Although the detailed reason is not clear, in the present invention, it is presumed that the mold filling property is improved by the antistatic function of the fatty acid glycerin ester having 6 to 30 carbon atoms.
本発明の製造方法においては、ポリオレフィン系樹脂粒子が、(B)無機ガスとして窒素ガスを使用して発泡粒子を製造した場合、発泡粒子の含水率を0.7重量%以上にする、分子量600以下の親水性物質を含むポリオレフィン系樹脂粒子を使用する。なお、親水性物質が無機塩などの場合は分子量に代えて式量を使用する。親水性物質の分子量が600を越えると、分子量が600以下の親水性物質を使用する場合に比較し、同じ発泡倍率の発泡粒子を得るためには多量の親水性物質が必要になり、さらに、得られる発泡成形体の表面性、融着性あるいは低収縮性が低下する。親水性物質が重合体の場合、その平均分子量は、たとえば、サーモフィッシャーサイエンティフィック製LCQアドバンテージなどの液体クロマトグラフ質量分析装置を使用し測定できる。 In the production method of the present invention, when the polyolefin resin particles are produced by using foamed particles using nitrogen gas as the inorganic gas (B), the water content of the foamed particles is set to 0.7% by weight or more. Polyolefin resin particles containing the following hydrophilic substances are used. When the hydrophilic substance is an inorganic salt or the like, the formula weight is used instead of the molecular weight. When the molecular weight of the hydrophilic substance exceeds 600, a larger amount of hydrophilic substance is required to obtain expanded particles having the same expansion ratio as compared with the case where a hydrophilic substance having a molecular weight of 600 or less is used. The surface property, fusing property or low shrinkage of the obtained foamed molded product is lowered. When the hydrophilic substance is a polymer, its average molecular weight can be measured using a liquid chromatograph mass spectrometer such as LCQ Advantage manufactured by Thermo Fisher Scientific.
本発明にいう親水性物質とは、無機ガスとして窒素ガスを使用して発泡粒子を製造した場合、ポリオレフィン系樹脂発泡粒子の含水率を0.7重量%以上にする親水性物質である。含水率は、ポリオレフィン系樹脂粒子として親水性物質とタルクをポリオレフィン樹脂100重量部に対し0.1重量部のみを添加した樹脂粒子を使用し、無機ガスとして窒素ガスを使用した以外は、製造するポリオレフィン系樹脂発泡粒子の製造条件と同じにして発泡粒子を製造する。但し、安定剤等が添加されているポリオレフィン樹脂を使用する場合、これら安定剤等を除去せずに測定する。これら安定剤等は含水率に対しほとんど影響しない。得られた発泡粒子の表面に付着した水を、室温において空気気流で脱水させたのち、その重量(W1)を測定する。さらにその発泡粒子を80℃のオーブン中で12時間乾燥させた時の重量(W2)を測定し、次式により算出する。
含水率(%)=(W1−W2)/W2×100
The hydrophilic substance referred to in the present invention is a hydrophilic substance that makes the water content of the polyolefin resin expanded particles 0.7% by weight or more when the expanded particles are produced using nitrogen gas as an inorganic gas. The water content is manufactured except that resin particles obtained by adding only 0.1 part by weight of a hydrophilic substance and talc as polyolefin resin particles to 0.1 parts by weight of polyolefin resin are used, and nitrogen gas is used as an inorganic gas. Foamed particles are produced under the same production conditions as for polyolefin resin foamed particles. However, when a polyolefin resin to which a stabilizer or the like is added is used, measurement is performed without removing the stabilizer or the like. These stabilizers have little influence on the moisture content. The water adhering to the surface of the obtained expanded particles is dehydrated with an air stream at room temperature, and the weight (W1) is measured. Furthermore, the weight (W2) when the foamed particles are dried in an oven at 80 ° C. for 12 hours is measured and calculated by the following formula.
Moisture content (%) = (W1-W2) / W2 × 100
水が含浸されるとポリオレフィン系樹脂粒子に無機ガスが含浸しやすくなると考えられ発泡倍率が向上すると考えられる。また、水は発泡剤となりうるので、多くの水を含浸することにより、発泡倍率が向上すると考えられる。特に無機ガスが、炭酸ガスである場合、水と共存しやすく、発泡倍率が大きく向上すると考えられる。 When water is impregnated, it is considered that the polyolefin resin particles are easily impregnated with inorganic gas, and the expansion ratio is considered to be improved. Further, since water can be a foaming agent, it is considered that the foaming ratio is improved by impregnating a large amount of water. In particular, when the inorganic gas is carbon dioxide, it tends to coexist with water, and the expansion ratio is considered to be greatly improved.
発泡粒子の含水率は0.7重量%以上であり、1重量%以上が好ましく、1.5重量%以上がより好ましい。また、10重量%以下が好ましく、8重量%以下がより好ましく、5重量%以下がさらに好ましい。含水率が0.7重量%未満の場合、発泡倍率が低いものしか得られない。10重量%を越える場合においては発泡後の発泡粒子内が低内圧となるために発泡粒子が収縮し易く、発泡後にオーブン養生等の処理をしても収縮が残ってしまうことがある。 The moisture content of the expanded particles is 0.7% by weight or more, preferably 1% by weight or more, and more preferably 1.5% by weight or more. Moreover, 10 weight% or less is preferable, 8 weight% or less is more preferable, and 5 weight% or less is further more preferable. When the water content is less than 0.7% by weight, only those having a low expansion ratio can be obtained. When the amount exceeds 10% by weight, the foamed particles after foaming have a low internal pressure, so that the foamed particles are easily shrunk, and shrinkage may remain even after treatment such as oven curing after foaming.
本発明に使用できる無機ガスとして窒素ガスを使用して発泡粒子を製造した場合、発泡粒子の含水率を0.7重量%以上にする、分子量が600以下の親水性物質の具体例としては、硼酸塩化合物である硼砂、硼酸亜鉛等が挙げられ、水酸基含有有機化合物であるグリセリン、ポリエチレングリコール等も挙げられる。さらに無機物に類されるものとして、塩化ナトリウム、塩化カルシウム、塩化マグネシウム、また有機物に類されるものとしてメラミン、イソシアヌル酸、メラミン・イソシアヌル酸縮合物、さらには重合体に類されるものとしてポリエチレンオキシド等のポリエーテル、ポリエーテルのポリプロピレン等への付加物やこれらのアロイ、エチレン(メタ)アクリル酸共重合体のアルカリ金属塩、ブタジエン(メタ)アクリル酸共重合体のアルカリ金属塩、カルボキシル化ニトリルゴムのアルカリ金属塩、イソブチレン−無水マレイン酸共重合体のアルカリ金属塩及びポリ(メタ)アクリル酸のアルカリ金属塩等が挙げられる。これら親水性物質は2種以上併用してもよい。 When producing expanded particles using nitrogen gas as an inorganic gas that can be used in the present invention, the specific example of a hydrophilic substance having a molecular weight of 600 or less, the water content of the expanded particles being 0.7% by weight or more, Examples thereof include borax, which is a borate compound, zinc borate and the like, and glycerin and polyethylene glycol which are hydroxyl group-containing organic compounds. In addition, inorganic substances such as sodium chloride, calcium chloride, magnesium chloride, organic substances similar to melamine, isocyanuric acid, melamine / isocyanuric acid condensates, and polymers similar to polyethylene oxide Polyethers such as polyethers, adducts of polyethers to polypropylene and the like, alloys thereof, alkali metal salts of ethylene (meth) acrylic acid copolymers, alkali metal salts of butadiene (meth) acrylic acid copolymers, carboxylated nitriles Examples thereof include alkali metal salts of rubber, alkali metal salts of isobutylene-maleic anhydride copolymer, and alkali metal salts of poly (meth) acrylic acid. Two or more of these hydrophilic substances may be used in combination.
これらの親水性物質のなかでは、硼砂、硼酸亜鉛等の硼酸塩化合物及び/又はグリセリン、ポリエチレングリコール等の水酸基含有有機化合物が好ましい。 Among these hydrophilic substances, borate compounds such as borax and zinc borate and / or hydroxyl group-containing organic compounds such as glycerin and polyethylene glycol are preferable.
これらの親水性物質を使用すると発泡粒子におけるセル径が適度の大きさで均一であるため、型内発泡成形体の収縮率が小さくなり、また、型内発泡成形体の表面が美麗にすることができる。 When these hydrophilic substances are used, the cell diameter in the expanded particles is uniform and appropriate, so that the shrinkage rate of the in-mold foam molding is reduced and the surface of the in-mold foam molding is to be beautiful. Can do.
親水性物質の添加量は、ポリオレフィン系樹脂100重量部に対して、0.005重量部以上2重量部以下であることが好ましく、より好ましくは0.005重量部以上1重量部以下、更に好ましくは0.01重量部以上0.5重量部以下である。ここで親水性物質の添加量とは、吸水していない状態での親水性物質の重量を指す。また結晶水を有する場合、結晶水を除いて親水性物質の添加量が計算される。 The addition amount of the hydrophilic substance is preferably 0.005 part by weight or more and 2 parts by weight or less, more preferably 0.005 part by weight or more and 1 part by weight or less, further preferably 100 parts by weight of the polyolefin resin. Is 0.01 parts by weight or more and 0.5 parts by weight or less. Here, the addition amount of the hydrophilic substance refers to the weight of the hydrophilic substance in a state where water is not absorbed. Moreover, when it has crystal water, the addition amount of a hydrophilic substance is calculated except crystal water.
親水性物質の添加量が0.005重量部より少ないと、ポリオレフィン系樹脂発泡粒子の発泡倍率を向上させることができなかったり、気泡の均一化効果が低減する傾向がある。添加量が2重量部を超えると、ポリオレフィン系樹脂発泡粒子の収縮が生じ易くなったり、ポリオレフィン系樹脂中への親水性物質の分散が不十分となる傾向がある。 When the addition amount of the hydrophilic substance is less than 0.005 parts by weight, the expansion ratio of the polyolefin resin expanded particles cannot be improved, or the effect of uniformizing the bubbles tends to be reduced. When the addition amount exceeds 2 parts by weight, the polyolefin resin expanded particles tend to shrink, and the hydrophilic substance tends to be insufficiently dispersed in the polyolefin resin.
本発明のポリオレフィン系樹脂粒子は他の添加剤が含有されていてもよい。好ましい添加剤は高級脂肪族アルコール、特には、炭素数が6〜24の脂肪族アルコールである。高級脂肪族アルコールは炭素数6以上30以下の脂肪酸のグリセリンエステルが有する帯電防止性能を向上させる。帯電防止性能向上のメカニズムは詳細には不明であるが、前記炭素数6以上30以下の脂肪酸のグリセリンエステルのポリオレフィン系樹脂中からのブリード性を調整していると考えられる。 The polyolefin resin particles of the present invention may contain other additives. A preferred additive is a higher aliphatic alcohol, particularly an aliphatic alcohol having 6 to 24 carbon atoms. A higher aliphatic alcohol improves the antistatic performance of a glycerin ester of a fatty acid having 6 to 30 carbon atoms. Although the mechanism for improving the antistatic performance is unknown in detail, it is considered that the bleeding property of the glycerin ester of the fatty acid having 6 to 30 carbon atoms in the polyolefin resin is adjusted.
高級脂肪族アルコールは、炭素数6以上30以下の脂肪酸のグリセリンエステルとの相溶性を合わせるほうが樹脂中への分散や、樹脂表層への溶出促進などの効率が良いと推測される。従って、グリセリンエステルを構成している脂肪酸と炭素数を合わせて使用することが好ましい。高級脂肪族アルコールは、ポリオレフィン系樹脂100重量部に対し、好ましくは0.1重量部以上5重量部以下、より好ましくは0.1重量部以上3重量部以下含まれる。 It is presumed that higher aliphatic alcohols are more efficient in dispersing in the resin and promoting elution into the resin surface layer when the compatibility with the glycerol ester of a fatty acid having 6 to 30 carbon atoms is matched. Therefore, it is preferable to use the fatty acid constituting the glycerin ester in combination with the number of carbon atoms. The higher aliphatic alcohol is preferably contained in an amount of 0.1 to 5 parts by weight, more preferably 0.1 to 3 parts by weight, based on 100 parts by weight of the polyolefin resin.
本発明のポリオレフィン系樹脂粒子には、必要に応じて有機顔料を加えてもよい。有機顔料としては、たとえばペリレン系、ポリアゾ系、キナクリドン系の有機顔料が例示されるが、これらに限定されるものではない。有機顔料の含有量はポリオレフィン系樹脂100重量部に対し、0.001重量部以上0.1重量部以下の範囲が分散性の点から好ましい。前記含有量が0.1重量部をこえるとポリオレフィン系樹脂発泡粒子の気泡径が微細となり、該ポリオレフィン系樹脂発泡粒子から得られるポリオレフィン系樹脂型内発泡成形体の表面性が劣り、見栄えが悪くなる傾向にある。 If necessary, an organic pigment may be added to the polyolefin resin particles of the present invention. Examples of the organic pigment include perylene-based, polyazo-based, and quinacridone-based organic pigments, but are not limited thereto. The content of the organic pigment is preferably from 0.001 part by weight to 0.1 part by weight with respect to 100 parts by weight of the polyolefin resin, from the viewpoint of dispersibility. When the content exceeds 0.1 parts by weight, the cell diameter of the polyolefin resin foamed particles becomes fine, the surface property of the polyolefin resin in-mold foam molded product obtained from the polyolefin resin foam particles is inferior, and the appearance is poor. Tend to be.
また、ポリオレフィン系樹脂粒子の製造の際にセル造核剤を添加することが、ポリオレフィン系樹脂発泡粒子とした時のセル径を所望の値に調整することが出来るため好ましい。セル造核剤としては、タルク、炭酸カルシウム、シリカ、カオリン、酸化チタン、ベントナイト、硫酸バリウム等の無機系造核剤が一般に使用される。セル造核剤の添加量は、使用するポリオレフィン系樹脂の種類、セル造核剤の種類により異なり一概には規定できないが、ポリオレフィン系樹脂100重量部に対して、概ね0.001重量部以上2重量部以下であることが好ましい。 Moreover, it is preferable to add a cell nucleating agent during the production of the polyolefin resin particles because the cell diameter when the polyolefin resin foamed particles can be adjusted to a desired value. As the cell nucleating agent, inorganic nucleating agents such as talc, calcium carbonate, silica, kaolin, titanium oxide, bentonite and barium sulfate are generally used. The amount of the cell nucleating agent added varies depending on the type of polyolefin resin to be used and the type of cell nucleating agent, and cannot be specified unconditionally, but is generally 0.001 part by weight or more with respect to 100 parts by weight of the polyolefin resin. It is preferable that it is below the weight part.
更に、ポリオレフィン系樹脂粒子の製造の際、必要により酸化防止剤、リン系加工安定剤、ラクトン系加工安定剤、金属不活性剤、ベンゾトリアゾール系紫外線吸収剤、ベンゾエート系光安定剤、ヒンダードアミン系光安定剤、難燃剤、難燃助剤、酸中和剤、結晶核剤等の添加剤を、ポリオレフィン系樹脂の特性を損なわない範囲内で添加することができる。 Furthermore, when producing polyolefin resin particles, an antioxidant, a phosphorus processing stabilizer, a lactone processing stabilizer, a metal deactivator, a benzotriazole UV absorber, a benzoate light stabilizer, a hindered amine light, if necessary. Additives such as stabilizers, flame retardants, flame retardant aids, acid neutralizers, and crystal nucleating agents can be added within a range that does not impair the properties of the polyolefin resin.
ポリオレフィン系樹脂発泡粒子は、ポリオレフィン樹脂から例えば以下のように製造される。 The polyolefin resin expanded particles are produced from a polyolefin resin, for example, as follows.
ポリオレフィン系樹脂は、所望の形状と大きさの発泡粒子を製造するために、押出機、ニーダー、バンバリーミキサー、ロール等を用いて溶融し、円柱、楕円、球、立方体、直方体等の形状と一定重量を有するポリオレフィン系樹脂粒子の形状に加工される。(A)炭素数6以上30以下の脂肪酸のグリセリンエステルや、(B)無機ガスとして窒素ガスを使用して発泡粒子を製造した場合、発泡粒子の含水率を0.7重量%以上にする、分子量が600以下の親水性物質や、他の樹脂、必要に応じて添加するその他の添加剤はプリブレンドした上で、押出ししてポリオレフィン系樹脂粒子としてもよいし、ポリオレフィン系樹脂と共に押出機等に供給してもよい。 Polyolefin resin is melted using an extruder, kneader, Banbury mixer, roll, etc. to produce foamed particles of the desired shape and size, and has a fixed shape such as a cylinder, ellipse, sphere, cube, cuboid, etc. It is processed into the shape of polyolefin resin particles having a weight. (A) When glycerin ester of fatty acid having 6 to 30 carbon atoms or (B) nitrogen gas is used as an inorganic gas to produce expanded particles, the moisture content of the expanded particles is 0.7% by weight or more. A hydrophilic substance having a molecular weight of 600 or less, other resins, and other additives to be added as necessary may be pre-blended and extruded to form polyolefin resin particles, or an extruder or the like together with the polyolefin resin. May be supplied.
ポリオレフィン系樹脂粒子の平均重量は、0.1〜30mgであることが好ましく、0.3〜10mgがより好ましい。樹脂粒子の平均重量は、ランダムに選んだ100粒のポリオレフィン系樹脂粒子から得られる平均であり、以下、mg/粒で表示する。 The average weight of the polyolefin resin particles is preferably 0.1 to 30 mg, and more preferably 0.3 to 10 mg. The average weight of the resin particles is an average obtained from 100 randomly selected polyolefin resin particles, and is hereinafter expressed in mg / grain.
得られたポリオレフィン系樹脂粒子は、耐圧容器内の水系分散媒に分散させ、無機ガスを添加し、ポリオレフィン系樹脂の軟化温度以上の温度まで加熱、加圧して発泡剤を樹脂粒子内に含浸させる。耐圧容器には特に制限はなく、ポリオレフィン系樹脂発泡粒子製造に必要な容器内圧力、容器内温度に耐えられるものであればよい。例えばオートクレーブ型の耐圧容器があげられる。水系分散媒としては水が好ましい。メタノール、エタノール、エチレングリコール、グリセリン等を水に添加した分散媒も水系分散媒として使用できる。 The obtained polyolefin resin particles are dispersed in an aqueous dispersion medium in a pressure vessel, an inorganic gas is added, and the resin particles are impregnated with a foaming agent by heating and pressurizing to a temperature equal to or higher than the softening temperature of the polyolefin resin. . There is no particular limitation on the pressure vessel, and any pressure vessel can be used as long as it can withstand the pressure in the vessel and the temperature in the vessel necessary for the production of polyolefin resin expanded particles. For example, an autoclave pressure vessel can be mentioned. Water is preferable as the aqueous dispersion medium. A dispersion medium in which methanol, ethanol, ethylene glycol, glycerin, or the like is added to water can also be used as the aqueous dispersion medium.
本発明においては、水及び無機ガスが発泡剤となりうる。水系分散媒中の水がポリオレフィン系樹脂粒子に含浸し発泡剤として作用する。他の含水率測定方法として、発泡直後のポリオレフィン系樹脂発泡粒子をポリマー用水分計、あるいはカールフィッシャー水分計などで測定することも可能である。無機ガスとしては、空気、窒素、炭酸ガス等が挙げられる。中でも発泡力が比較的大きく、環境負荷が小さく、燃焼危険性も無いことから、炭酸ガスが望ましい。発泡剤として、水と炭酸ガスを併用することで、発泡力が大きくなり、発泡核剤の添加量を少なくすることができる傾向がある。この結果、高発泡倍率であって平均気泡径が大きい発泡粒子を得ることができ、2次発泡性も良好なものとなる傾向がある。 In the present invention, water and inorganic gas can serve as a foaming agent. Water in the aqueous dispersion medium is impregnated into the polyolefin resin particles and acts as a foaming agent. As another moisture content measuring method, it is also possible to measure the polyolefin resin expanded particles immediately after foaming with a polymer moisture meter or a Karl Fischer moisture meter. Examples of the inorganic gas include air, nitrogen, and carbon dioxide gas. Among them, carbon dioxide gas is desirable because it has a relatively large foaming power, a small environmental load, and no danger of combustion. By using water and carbon dioxide as a foaming agent, the foaming power tends to increase, and the amount of foaming nucleating agent added tends to be reduced. As a result, expanded particles having a high expansion ratio and a large average cell diameter can be obtained, and the secondary foamability tends to be good.
水及び無機ガスを発泡剤として使用していれば、他の物理発泡剤を併用してもよい。他の物理発泡剤としては、プロパン、n−ブタン、iso−ブタン、ペンタン等の飽和炭化水素類、ジメチルエーテル等のエーテル類、メタノール、エタノール等のアルコール類が挙げられる。 If water and inorganic gas are used as the foaming agent, other physical foaming agents may be used in combination. Examples of other physical foaming agents include saturated hydrocarbons such as propane, n-butane, iso-butane and pentane, ethers such as dimethyl ether, and alcohols such as methanol and ethanol.
水系分散媒中、ポリオレフィン系樹脂粒子同士の合着を防止するために、分散剤を使用することが好ましい。分散剤として、第三リン酸カルシウム、第三リン酸マグネシウム、酸化チタン、塩基性炭酸マグネシウム、炭酸カルシウム、硫酸バリウム、カオリン、タルク、クレー等の無機系分散剤が例示できる。これらの中、第三リン酸カルシウム、カオリン、硫酸バリウムが少ない使用量でも水系分散物を安定的に放出させることができるため好ましい。 In order to prevent coalescence of polyolefin resin particles in the aqueous dispersion medium, it is preferable to use a dispersant. Examples of the dispersant include inorganic dispersants such as tricalcium phosphate, tribasic magnesium phosphate, titanium oxide, basic magnesium carbonate, calcium carbonate, barium sulfate, kaolin, talc, and clay. Among these, tricalcium phosphate, kaolin, and barium sulfate are preferable because the aqueous dispersion can be stably released even with a small amount of use.
また、分散剤と共に分散助剤を使用することが好ましい。分散助剤の例としては、N−アシルアミノ酸塩、アルキルエーテルカルボン酸塩、アシル化ペプチド等のカルボン酸塩型、アルキルスルホン酸塩、アルキルベンゼンスルホン酸塩、アルキルナフタレンスルホン酸塩、スルホコハク酸塩等のスルホン酸塩型、硫酸化油、アルキル硫酸塩、アルキルエーテル硫酸塩、アルキルアミド硫酸塩等の硫酸エステル型、アルキルリン酸塩、ポリオキシエチレンリン酸塩、アルキルアリルエーテル硫酸塩等のリン酸エステル型等の陰イオン界面活性剤をあげることができる。また、マレイン酸共重合体塩、ポリアクリル酸塩等のポリカルボン酸型高分子界面活性剤、ポリスチレンスルホン酸塩、ナフタルスルホン酸ホルマリン縮合物塩などの多価陰イオン高分子界面活性剤も使用することができる。 Further, it is preferable to use a dispersion aid together with the dispersant. Examples of dispersing aids include N-acyl amino acid salts, alkyl ether carboxylates, carboxylate types such as acylated peptides, alkyl sulfonates, alkyl benzene sulfonates, alkyl naphthalene sulfonates, sulfosuccinates, etc. Sulfate type, sulfate oil, alkyl sulfate, alkyl ether sulfate, sulfate ester type such as alkylamide sulfate, phosphoric acid such as alkyl phosphate, polyoxyethylene phosphate, alkyl allyl ether sulfate An anionic surfactant such as an ester type can be exemplified. Also, polycarboxylic acid type polymer surfactants such as maleic acid copolymer salts and polyacrylates, polyvalent anionic polymer surfactants such as polystyrene sulfonates and naphthalsulfonic acid formalin condensate salts, etc. Can be used.
分散助剤として、スルホン酸塩型の陰イオン界面活性剤を使用することが好ましく、さらには、アルキルスルホン酸塩、アルキルベンゼンスルホン酸塩から選ばれた1種もしくは2種以上の混合物を用いるのが好ましい。アルキルスルホン酸塩を使用することがより好ましく、疎水基として炭素数10〜18の直鎖状の炭素鎖を持つアルキルスルホン酸塩を使用することが、発泡粒子に付着する分散剤を低減できるため特に好ましい。 As the dispersion aid, it is preferable to use a sulfonate type anionic surfactant, and it is also preferable to use one or a mixture of two or more selected from alkyl sulfonates and alkylbenzene sulfonates. preferable. It is more preferable to use an alkyl sulfonate, and the use of an alkyl sulfonate having a linear carbon chain having 10 to 18 carbon atoms as a hydrophobic group can reduce the dispersant adhering to the expanded particles. Particularly preferred.
これらの中でも、分散剤として第三リン酸カルシウム、第三リン酸マグネシウム、硫酸バリウムまたはカオリンから選ばれる一種以上と、分散助剤としてn−パラフィンスルホン酸ソーダを併用することが好ましい。 Among these, it is preferable to use one or more selected from tricalcium phosphate, tribasic magnesium phosphate, barium sulfate or kaolin as a dispersant and n-paraffin sulfonic acid soda as a dispersion aid.
分散剤や分散助剤の使用量は、その種類や、用いるポリオレフィン系樹脂の種類と使用量によって異なる。通常、水系分散媒100重量部に対して、分散剤0.1重量部以上5重量部以下を添加することが好ましく、さらには0.2重量部以上3重量部以下を配合することが好ましく、分散助剤0.001重量部以上0.3重量部以下を添加することが好ましく、さらには0.001重量部以上0.1重量部以下を配合することが好ましい。また、ポリオレフィン系樹脂粒子は、水系分散媒中での分散性を良好なものにするために、通常、水系分散媒100重量部に対して、20重量部以上100重量部以下使用するのが好ましい。 The amount of the dispersant and the dispersion aid used varies depending on the type and the type and amount of the polyolefin resin used. Usually, it is preferable to add 0.1 parts by weight or more and 5 parts by weight or less of the dispersant with respect to 100 parts by weight of the aqueous dispersion medium, and more preferably 0.2 parts by weight or more and 3 parts by weight or less. It is preferable to add 0.001 part by weight or more and 0.3 part by weight or less of a dispersion aid, and it is more preferable to add 0.001 part by weight or more and 0.1 part by weight or less. The polyolefin resin particles are usually preferably used in an amount of 20 to 100 parts by weight with respect to 100 parts by weight of the aqueous dispersion medium in order to improve the dispersibility in the aqueous dispersion medium. .
水系分散媒に分散し、無機ガスが添加された後、分散系全体を加熱、加圧する。これにより発泡剤がポリオレフィン系樹脂粒子に含浸される。加熱温度は原料樹脂種、添加剤、発泡倍率、使用する発泡剤種により、適宜決められる。加熱温度はポリオレフィン系樹脂粒子の軟化温度以上、好ましくはポリオレフィン系樹脂粒子の融点−25℃以上でポリオレフィン系樹脂粒子の融点+25℃以下の範囲、更に好ましくはポリオレフィン系樹脂粒子の融点−15℃以上でポリオレフィン系樹脂粒子の融点+15℃以下の範囲から選択される。無機ガスでは加熱温度は高い傾向がある。また高温であるほど得られる発泡粒子の発泡倍率が高くなる傾向がある。 After dispersing in an aqueous dispersion medium and adding an inorganic gas, the entire dispersion is heated and pressurized. Thereby, the polyolefin resin particles are impregnated with the foaming agent. The heating temperature is appropriately determined depending on the raw material resin type, the additive, the expansion ratio, and the foaming agent type to be used. The heating temperature is higher than the softening temperature of the polyolefin resin particles, preferably in the range of the melting point of the polyolefin resin particles −25 ° C. or higher and the melting point of the polyolefin resin particles + 25 ° C. or lower, more preferably the melting point of the polyolefin resin particles −15 ° C. or higher. The melting point of the polyolefin resin particles is selected from the range of 15 ° C. or lower. Inorganic gas tends to have a high heating temperature. Moreover, there exists a tendency for the expansion ratio of the expanded particle obtained so that it is high temperature to become high.
発泡剤が含浸された耐圧容器内のポリオレフィン系樹脂粒子を耐圧容器の内圧よりも低圧の雰囲気に放出することにより、ポリオレフィン系樹脂発泡粒子を得ることが出来る。耐圧容器の内圧よりも低圧の雰囲気とは、耐圧容器中のポリオレフィン系樹脂粒子を含んでなる水系分散物を放出する低圧の雰囲気であるかぎりとくに制限はない。たとえば大気中に放出する際には大気圧雰囲気、揮発性発泡剤を回収するために密閉系内に放出する場合には密閉系内の雰囲気などのことである。低圧の雰囲気に放出して発泡したポリオレフィン系樹脂発泡粒子は、水分を除去され、さらに乾燥される。 By releasing the polyolefin-based resin particles in the pressure-resistant container impregnated with the foaming agent into an atmosphere having a pressure lower than the internal pressure of the pressure-resistant container, the polyolefin-based resin expanded particles can be obtained. The atmosphere having a pressure lower than the internal pressure of the pressure vessel is not particularly limited as long as it is a low pressure atmosphere that discharges the aqueous dispersion containing the polyolefin resin particles in the pressure vessel. For example, an atmospheric pressure atmosphere when released into the atmosphere, and an atmosphere within the closed system when released into a closed system in order to recover the volatile foaming agent. The expanded polyolefin resin foam particles released into a low-pressure atmosphere are dehydrated and further dried.
以下に樹脂粒子への発泡剤の含浸工程と樹脂粒子の発泡工程の具体例を挙げる。ポリオレフィン系樹脂100重量部に対し、炭素数6以上30以下の脂肪酸のグリセリンエステルを好ましくは0.1重量部以上5重量部以下、分子量600以下の親水性物質を好ましくは0.05重量部以上2重量部以下、および発泡核剤を含有させたポリオレフィン系樹脂粒子を、耐圧容器内の水系分散媒に分散させ、無機ガスを添加し、ポリオレフィン系樹脂の軟化温度以上の温度まで加熱、加圧して発泡剤をポリオレフィン系樹脂粒子内に含浸させる。さらに窒素もしくは空気を圧入することで耐圧容器内の内圧を高めた後、耐圧容器の内圧よりも低い圧力域に放出してポリオレフィン系樹脂発泡粒子を製造する。低圧域に放出する前に窒素もしくは空気を圧入して、耐圧容器内の内圧を高めることにより、発泡時の圧力開放速度を調節し、発泡倍率や平均気泡径の調整を行うことができる。 Specific examples of the step of impregnating the resin particles with the foaming agent and the step of foaming the resin particles are given below. Preferably, the glycerin ester of a fatty acid having 6 to 30 carbon atoms is preferably 0.1 to 5 parts by weight and the hydrophilic substance having a molecular weight of 600 or less is preferably 0.05 parts by weight or more with respect to 100 parts by weight of the polyolefin resin. 2 parts by weight or less and polyolefin resin particles containing a foam nucleating agent are dispersed in an aqueous dispersion medium in a pressure-resistant vessel, an inorganic gas is added, and heated and pressurized to a temperature equal to or higher than the softening temperature of the polyolefin resin. Then, the foaming agent is impregnated into the polyolefin resin particles. Further, the internal pressure in the pressure vessel is increased by press-fitting nitrogen or air, and then released into a pressure region lower than the internal pressure of the pressure vessel to produce polyolefin resin expanded particles. Before releasing into the low-pressure region, nitrogen or air is injected to increase the internal pressure in the pressure-resistant container, thereby adjusting the pressure release speed during foaming and adjusting the foaming ratio and the average cell diameter.
また、無機ガスとして、常温で気体の炭酸ガスを用いる場合は、ポリオレフィン系樹脂粒子と水系分散媒を耐圧容器に投入したのち、炭酸ガスを耐圧容器内に導入すれば良い。例えば、耐圧容器にポリオレフィン系樹脂粒子、水系分散媒、分散剤等を仕込んだ後、耐圧容器内を真空引きした後、1〜2MPa程度の炭酸ガスを導入し、ポリオレフィン系樹脂の軟化温度以上の温度まで加熱する。加熱することによって耐圧容器内の圧力が約1.5〜3MPa程度まで上がる。発泡させる温度付近にてさらに炭酸ガスを追加して所望の発泡させる圧力に調整、さらに温度調整を行った後、耐圧容器の内圧よりも低い圧力雰囲気下に放出してポリオレフィン系樹脂発泡粒子を得る。或いは、耐圧容器にポリオレフィン系樹脂粒子、水系分散媒、必要に応じて分散剤等を仕込んだ後、必要に応じて耐圧容器内を真空引きした後、ポリオレフィン系樹脂の軟化温度以上の温度まで加熱しながら炭酸ガスを導入してもよい。 In addition, when carbon dioxide gas that is gaseous at normal temperature is used as the inorganic gas, the carbon dioxide gas may be introduced into the pressure vessel after the polyolefin resin particles and the aqueous dispersion medium are introduced into the pressure vessel. For example, after preparing polyolefin resin particles, aqueous dispersion medium, dispersant, etc. in a pressure vessel, evacuating the inside of the pressure vessel, introducing carbon dioxide of about 1 to 2 MPa, and having a temperature higher than the softening temperature of the polyolefin resin. Heat to temperature. By heating, the pressure in the pressure vessel rises to about 1.5 to 3 MPa. Carbon dioxide is added near the foaming temperature to adjust to the desired foaming pressure, and after adjusting the temperature, it is discharged under a pressure atmosphere lower than the internal pressure of the pressure vessel to obtain polyolefin resin foamed particles. . Alternatively, after preparing polyolefin resin particles, water-based dispersion medium, and dispersing agent if necessary in a pressure vessel, evacuating the pressure vessel if necessary, then heating to a temperature higher than the softening temperature of the polyolefin resin Carbon dioxide gas may be introduced while being introduced.
本発明のポリオレフィン系樹脂発泡粒子は、上述のような、耐圧容器内にポリオレフィン系樹脂粒子を水系分散媒に分散させ、無機ガスを添加し、ポリオレフィン系樹脂粒子の軟化温度以上の温度まで加熱、加圧してポリオレフィン系樹脂粒子に発泡剤を含浸させ、発泡剤が含浸されたポリオレフィン系樹脂粒子を耐圧容器の内圧よりも低い圧力域に放出する工程を経て得られる。 The polyolefin-based resin expanded particles of the present invention, as described above, disperse the polyolefin-based resin particles in an aqueous dispersion medium in a pressure-resistant container, add an inorganic gas, and heat to a temperature equal to or higher than the softening temperature of the polyolefin-based resin particles. It is obtained through a process of applying pressure to impregnate the polyolefin resin particles with a foaming agent and releasing the polyolefin resin particles impregnated with the foaming agent into a pressure range lower than the internal pressure of the pressure vessel.
しかし、高発泡倍率の発泡粒子が必要な場合、この発泡粒子をさらに発泡させてもよい。耐圧容器内にポリオレフィン系樹脂粒子を水系分散媒に分散させ、無機ガスを添加し、ポリオレフィン系樹脂粒子の軟化温度以上の温度まで加熱、加圧してポリオレフィン系樹脂粒子に発泡剤を含浸させ、発泡剤が含浸されたポリオレフィン系樹脂粒子を耐圧容器の内圧よりも低い圧力域に放出させて発泡させることを一段発泡と称し、一段発泡により得られる発泡粒子を一段発泡粒子と呼ぶ場合がある。一段発泡粒子さらに発泡させることを二段発泡と称し、二段発泡によって得られた発泡粒子を二段発泡粒子と呼ぶ場合がある。通常、二段発泡は、一段発泡粒子を耐圧容器内にて空気等の無機ガスにて加圧し、内圧を付与させたのち、加熱することによりなされる。本発明のように発泡倍率が20倍以上の発泡粒子を製造する場合、二段発泡を採用することが好ましい。 However, if expanded particles with a high expansion ratio are required, the expanded particles may be further expanded. Disperse polyolefin resin particles in an aqueous dispersion medium in a pressure-resistant container, add inorganic gas, heat and press to a temperature above the softening temperature of the polyolefin resin particles, impregnate the polyolefin resin particles with a foaming agent, and foam The release of the polyolefin resin particles impregnated with the agent into a pressure range lower than the internal pressure of the pressure vessel is referred to as one-stage foaming, and the foamed particles obtained by one-stage foaming are sometimes referred to as single-stage foamed particles. Further expansion of the single-stage expanded particles is sometimes referred to as two-stage expansion, and the expanded particles obtained by the two-stage expansion may be referred to as two-stage expanded particles. Usually, the two-stage foaming is performed by pressurizing the first-stage foamed particles with an inorganic gas such as air in a pressure resistant container, applying an internal pressure, and then heating. When producing expanded particles having an expansion ratio of 20 times or more as in the present invention, it is preferable to employ two-stage expansion.
本発明においては、最終的に得られる発泡粒子の発泡倍率は20倍以上である。最終的に得られる発泡粒子の発泡倍率は60倍以下が好ましい。発泡倍率が20倍未満の場合は、軽量化のメリットが得られず、また得られるポリオレフィン系樹脂型内発泡成形体の柔軟性、緩衝特性などが不充分となる傾向がある。発泡倍率が60倍を越える場合は、得られるポリオレフィン系樹脂型内発泡成形体の寸法精度、機械的強度、耐熱性などが不充分となる傾向がある。ポリオレフィン系樹脂発泡粒子の発泡倍率の測定法は後記する。 In the present invention, the expansion ratio of the finally obtained expanded particles is 20 times or more. The expansion ratio of the expanded particles finally obtained is preferably 60 times or less. When the expansion ratio is less than 20 times, the advantage of weight reduction cannot be obtained, and the flexibility and buffering properties of the resulting polyolefin resin-in-mold foam-molded product tend to be insufficient. When the expansion ratio exceeds 60 times, the dimensional accuracy, mechanical strength, heat resistance and the like of the obtained polyolefin resin in-mold foam molded product tend to be insufficient. A method for measuring the expansion ratio of the polyolefin resin expanded particles will be described later.
本発明によって得られるポリオレフィン系樹脂発泡粒子の平均気泡径は50μm以上800μm以下であることが好ましく、より好ましくは100μm以上600μm以下、さらに好ましくは200μm以上500μm以下である。平均気泡径が50μm未満の場合、得られるポリオレフィン系樹脂型内発泡成形体の形状が歪む、表面にしわが発生するなどの問題が生じる場合があり、800μmを越える場合、得られるポリオレフィン系樹脂型内発泡成形体の緩衝特性が低下する場合がある。平均気泡径は、ポリオレフィン系樹脂発泡粒子の切断面について、表層部を除く部分についてASTM D3576に従い測定する。 The average cell diameter of the polyolefin resin expanded particles obtained by the present invention is preferably 50 μm or more and 800 μm or less, more preferably 100 μm or more and 600 μm or less, and further preferably 200 μm or more and 500 μm or less. If the average cell diameter is less than 50 μm, there may be problems such as distortion of the shape of the foamed molded product in the polyolefin resin mold obtained and wrinkles on the surface. The cushioning characteristics of the foamed molded product may be deteriorated. The average cell diameter is measured in accordance with ASTM D3576 with respect to the cut surface of the polyolefin-based resin expanded particles, except for the surface layer portion.
本発明のポリオレフィン系樹脂発泡粒子の連泡率は0〜12%であることが好ましく、より好ましくは0〜8%、さらに好ましくは0〜5%である。連泡率が12%を超えると、型内成形時に蒸気加熱による発泡性に劣り、得られたポリオレフィン系樹脂型内発泡成形体が収縮してしまう傾向にある。 The open cell ratio of the polyolefin resin expanded particles of the present invention is preferably 0 to 12%, more preferably 0 to 8%, and still more preferably 0 to 5%. When the open cell ratio exceeds 12%, the foamability by steam heating is inferior at the time of in-mold molding, and the obtained polyolefin resin in-mold foam molded product tends to shrink.
本発明のポリオレフィン系樹脂発泡粒子は、示差走査熱量測定によって得られるDSC曲線において、2つ以上の融点を示す結晶構造を有することが好ましい。2つ以上の融点を示す結晶構造を有するポリオレフィン系樹脂発泡粒子の場合、型内発泡成形性が良く、機械的強度や耐熱性の良好なポリオレフィン系樹脂型内発泡成形体が得られる傾向にある。ここで、ポリオレフィン系樹脂発泡粒子の示差走査熱量測定によって得られるDSC曲線とは、ポリオレフィン系樹脂発泡粒子1〜10mgを示差走査熱量計によって10℃/分の昇温速度で40℃から220℃まで昇温したときに得られるDSC曲線のことである。このDSC曲線において、現れる融解ピークの示す温度が融点である。 The polyolefin resin expanded particles of the present invention preferably have a crystal structure showing two or more melting points in a DSC curve obtained by differential scanning calorimetry. In the case of polyolefin-based resin expanded particles having a crystal structure exhibiting two or more melting points, there is a tendency to obtain a polyolefin-based in-mold expanded molded article having good in-mold foam moldability and good mechanical strength and heat resistance. . Here, the DSC curve obtained by differential scanning calorimetry of polyolefin resin expanded particles refers to 1 to 10 mg of polyolefin resin expanded particles from 40 ° C. to 220 ° C. at a rate of temperature increase of 10 ° C./min with a differential scanning calorimeter. It is a DSC curve obtained when the temperature is raised. In this DSC curve, the temperature indicated by the melting peak that appears is the melting point.
前記のごとく2つ以上の融点を示す結晶構造を有するポリオレフィン系樹脂発泡粒子は、発泡時の耐圧容器内温度を適切な値に設定することにより容易に得られる。適切な温度は用いる発泡剤や基材となるポリオレフィン系樹脂の種類によって異なるが、例えば発泡剤に炭酸ガスを用い、ポリオレフィン系樹脂として、ポリプロピレン系樹脂を用いる場合、ポリプロピレン系樹脂の融点以上であって融解終了温度未満、好ましくは融解終了温度−2℃以下の温度から選定される。ここで、前記融解終了温度とは、示差走査熱量計によってポリオレフィン系樹脂1〜10mgを40℃から220℃まで10℃/分の速度で昇温し、その後40℃まで10℃/分の速度で冷却し、再度220℃まで10℃/分の速度で昇温した時に得られる融解ピーク曲線が高温側でベースラインの位置に戻ったときの温度である。 As described above, the polyolefin resin foamed particles having a crystal structure exhibiting two or more melting points can be easily obtained by setting the temperature in the pressure vessel at the time of foaming to an appropriate value. The appropriate temperature varies depending on the foaming agent used and the type of polyolefin resin used as the base material.For example, when carbon dioxide is used as the foaming agent and a polypropylene resin is used as the polyolefin resin, the temperature is higher than the melting point of the polypropylene resin. The melting end temperature is lower than the melting end temperature, preferably the melting end temperature is −2 ° C. or lower. Here, the melting end temperature is 1 to 10 mg of polyolefin resin by a differential scanning calorimeter at a rate of 10 ° C./min from 40 ° C. to 220 ° C., and then at a rate of 10 ° C./min to 40 ° C. This is the temperature at which the melting peak curve obtained when cooling and again raising the temperature to 220 ° C. at a rate of 10 ° C./min returned to the baseline position on the high temperature side.
本発明で得られるポリオレフィン系樹脂発泡粒子は金型に充填し加熱することにより、発泡粒子間の隙間がなくなるように発泡させ、且つ、発泡粒子間を融着させ任意の形状に成形すること、いわゆる型内成形をすることができる。 The polyolefin-based resin expanded particles obtained in the present invention are filled in a mold and heated, so that there are no gaps between the expanded particles, and the expanded particles are fused and molded into an arbitrary shape, So-called in-mold molding can be performed.
本発明のポリオレフィン系樹脂発泡粒子は、金型充填性に優れている。本発明に言う金型充填性とは、ポリオレフィン系樹脂発泡粒子を型内発泡成形に用いる場合に、金型内容積に対しどれだけ多くの体積のポリオレフィン系樹脂発泡粒子が金型細部まで効率的に充填されるかを示している。 The polyolefin resin expanded particles of the present invention are excellent in mold filling properties. The mold filling property referred to in the present invention is that when polyolefin resin foamed particles are used for in-mold foam molding, how much volume of polyolefin resin foamed particles is more efficient than the mold inner volume. Indicates whether it is filled.
簡易的には、金型の薄肉部すなわちポリオレフィン系樹脂発泡粒子径の2倍〜4倍の厚みの部位に発泡粒子が欠けることなく充填されるか否かで、金型充填性を評価しうる。
In a simple manner, the mold filling property can be evaluated based on whether or not the foamed particles are filled in the thin wall portion of the mold, that is, the portion having a
型内発泡成形に使用する金型としては、蒸気等加熱媒体は流通することができるが、ポリオレフィン系樹脂発泡粒子は外部に流出しない金型が通常用いられる。通常、加熱媒体として0.05〜0.5MPa(G)程度の水蒸気が用いられ、3〜30秒程度の加熱時間で成形される。 As a mold used for in-mold foam molding, a heating medium such as steam can be circulated, but a mold in which polyolefin resin foamed particles do not flow out is usually used. Usually, steam of about 0.05 to 0.5 MPa (G) is used as a heating medium, and the molding is performed in a heating time of about 3 to 30 seconds.
型内発泡成形において用いる発泡粒子に対しては次のような従来既知の処理を行うことができる。イ)そのまま用いる方法、ロ)あらかじめポリオレフィン系樹脂発泡粒子中に空気等の無機ガスを圧入し、発泡能を付与する方法、ハ)ポリオレフィン系樹脂発泡粒子を圧縮状態で金型内に充填し成形する方法。これらの中でも、あらかじめポリオレフィン系樹脂発泡粒子中に空気等の無機ガスを圧入し、発泡能を付与するロ)の方法が好適である。 The following conventionally known treatments can be performed on the expanded particles used in the in-mold foam molding. B) A method to use as it is, b) A method in which an inorganic gas such as air is press-fitted into polyolefin resin foam particles in advance to give foaming ability, and c) A polyolefin resin foam particle is filled in a mold in a compressed state and molded. how to. Among these, the method (b) in which an inorganic gas such as air is previously press-fitted into the polyolefin resin foamed particles to impart foaming ability is preferable.
具体的には次の型内発泡成形法によって型内発泡成形体を得ることが出来る。
1)ポリオレフィン系樹脂発泡粒子を耐圧容器内で空気加圧し、ポリオレフィン系樹脂発泡粒子中に空気を圧入することにより発泡能を付与する。
2)得られたポリオレフィン系樹脂発泡粒子を2つの金型からなる、閉鎖しうるが密閉し得ない成形空間内に充填する。
3)水蒸気などを加熱媒体として0.2〜0.4MPa(G)程度のスチーム圧で3〜30秒程度の加熱時間で成形し、ポリオレフィン系樹脂発泡粒子同士を融着させる。
4)金型を水冷する。
5)金型を開いて、型内発泡成形体を取り出す。
Specifically, an in-mold foam molded product can be obtained by the following in-mold foam molding method.
1) Foaming ability is imparted by pressurizing the polyolefin resin foamed particles with air in a pressure resistant container and pressurizing the air into the polyolefin resin foamed particles.
2) The obtained polyolefin resin expanded particles are filled into a molding space composed of two molds, which can be closed but cannot be sealed.
3) Molding with a steam pressure of about 0.2 to 0.4 MPa (G) and a heating time of about 3 to 30 seconds using steam or the like as a heating medium, and fusing the polyolefin-based resin expanded particles together.
4) Cool the mold with water.
5) Open the mold and take out the in-mold foam molding.
得られるポリオレフィン系樹脂型内発泡成形体の発泡倍率は、特に限定されないが、30〜60倍が好ましく、さらには35〜55倍が好ましく、35〜50倍がより好ましく、有用である。 The expansion ratio of the obtained polyolefin-based resin mold is not particularly limited, but is preferably 30 to 60 times, more preferably 35 to 55 times, more preferably 35 to 50 times, and useful.
本発明で得られるポリオレフィン系樹脂発泡粒子を用いたポリオレフィン系樹脂型内発泡成形体は、断熱材、緩衝包装材、自動車内装部材、自動車バンパー用芯材などの用途に用いることができる。高発泡倍率の型内発泡成形体が使用されることが多い緩衝包装材に、本発明で得られるポリオレフィン系樹脂発泡粒子を用いたポリオレフィン系樹脂型内発泡成形体を使用することは、特に望ましい使用法である。 The polyolefin resin-in-mold foam-molded article using the polyolefin resin foam particles obtained in the present invention can be used for applications such as a heat insulating material, a buffer packaging material, an automobile interior member, and an automobile bumper core material. It is particularly desirable to use a polyolefin resin in-mold foam molded product using the polyolefin resin foam particles obtained in the present invention for a buffer packaging material in which a high expansion ratio in-mold foam molded product is often used. Usage.
以下、実施例および比較例をあげて、本発明をさらに具体的に説明するが、本発明はかかる実施例のみに限定されるものではない。なお、実施例および比較例における評価は、つぎの方法によった。 Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to such examples. The evaluation in the examples and comparative examples was based on the following method.
(含水率)
ポリオレフィン系樹脂粒子として親水性物質とタルクをポリオレフィン樹脂100重量部に対し0.1重量部のみを添加した樹脂粒子を使用し、無機ガスとして窒素ガスを使用した以外は、製造するポリオレフィン系樹脂発泡粒子の製造条件と同じにして発泡粒子を製造する。但し、安定剤等が添加されているポリオレフィン樹脂を使用する場合、これら安定剤等を除去せずに測定する。これら安定剤等は含水率に対しほとんど影響しない。得られた発泡粒子の表面に付着した水を、室温において空気気流で脱水させたのち、その重量(W1)を測定する。発泡粒子表面に水が付着していると粒子同士が水の作用でくっついているが、脱水すると粒子がバラバラになるので脱水時点は容易に判断できる。さらにその発泡粒子を80℃のオーブン中で12時間乾燥させた時の重量(W2)を測定する。含水率を次式により算出する。
含水率(%)=(W1−W2)/W2×100
(Moisture content)
Polyolefin resin foam to be produced, except that resin particles containing only 0.1 parts by weight of a hydrophilic substance and talc as polyolefin resin particles are added to 100 parts by weight of polyolefin resin, and nitrogen gas is used as the inorganic gas. Foamed particles are produced in the same manner as the particle production conditions. However, when a polyolefin resin to which a stabilizer or the like is added is used, measurement is performed without removing the stabilizer or the like. These stabilizers have little influence on the moisture content. The water adhering to the surface of the obtained expanded particles is dehydrated with an air stream at room temperature, and the weight (W1) is measured. When water adheres to the surface of the foamed particles, the particles adhere to each other due to the action of water, but when dehydrated, the particles fall apart, so the dehydration time can be easily determined. Furthermore, the weight (W2) when the expanded particles are dried in an oven at 80 ° C. for 12 hours is measured. The water content is calculated by the following formula.
Moisture content (%) = (W1-W2) / W2 × 100
(発泡倍率)
3〜10gの発泡粒子を60℃で6時間乾燥したのち重量w(g)を測定後、水没法にて体積v(cm3)を測定し、発泡粒子の真比重ρb=w/vを求め、発泡前のポリプロピレン系樹脂粒子の密度ρrとの比から発泡倍率K=ρr/ρbを求めた。
(Foaming ratio)
After drying 3 to 10 g of expanded particles at 60 ° C. for 6 hours and measuring the weight w (g), the volume v (cm 3 ) is measured by a submerging method, and the true specific gravity ρ b = w / v of the expanded particles is set. The expansion ratio K = ρ r / ρ b was determined from the ratio with the density ρ r of the polypropylene resin particles before foaming.
(金型充填性)
金型充填性評価用金型として、図1に示す複数の仕切板を有する物品収納用緩衝箱を用いて、得られた発泡粒子を型内成形した。仕切板部分における発泡粒子の充填を目視により観察し、金型充填性を評価した。緩衝箱は、長さ350mm×幅320mm深さ180mmの大きさで、内部に幅さ方向に平行な6組の仕切板を有している。各仕切板は形状及び寸法が異なるが最も薄い仕切板は仕切板2で底部の厚さが8mmで上部の厚さが5mmであった。仕切板2の上部は最も発泡粒子が充填しにくい部分と考えられ、この部分の粒子の充填性を以下の評価により金型充填性とした。なお、以上の寸法は金型における寸法である。また、発泡粒子の充填口は金型において緩衝箱の底部相当部分に6カ所設けた。
○:金型通りに発泡粒子が充填している
×:金型通りに発泡粒子が充填しておらず、発泡粒子が欠けたように見える部分がある。
(Mold filling property)
The obtained foamed particles were molded in-mold using a buffer box for storing articles having a plurality of partition plates shown in FIG. 1 as a mold for mold filling evaluation. The filling of the expanded particles in the partition plate portion was visually observed to evaluate the mold filling property. The buffer box has a length of 350 mm × width of 320 mm and depth of 180 mm, and has six sets of partition plates parallel to the width direction inside. Each partition plate is different in shape and size, but the thinnest partition plate is the
○: Expanded particles are filled according to the mold ×: Expanded particles are not filled according to the mold, and there are portions where the expanded particles appear to be chipped.
(寸法収縮率)
寸法収縮率評価用金型として、金型寸法が400mm×300mm×20mmの直方体(プランク)作製用金型を用いて得られた発泡粒子を型内成形した。成形後、23℃で2時間静置し、つぎに65℃で6時間養生したのち、23℃の室内に4時間放置して得られた型内発泡成形体の長手寸法を測定し、対応する金型寸法に対する、金型寸法と型内発泡成形体の寸法との差の割合を対金型寸法収縮率とし、以下の基準で評価した。
◎:対金型寸法収縮率が4%以下
〇:対金型寸法収縮率が4%を超えて7%以下
×:対金型寸法収縮率が7%より大きい
(Dimension shrinkage)
As the dimensional shrinkage evaluation mold, foamed particles obtained using a rectangular parallelepiped (plank) mold having a mold size of 400 mm × 300 mm × 20 mm were molded in-mold. After molding, it is allowed to stand at 23 ° C. for 2 hours, then cured at 65 ° C. for 6 hours, and then measured for the longitudinal dimension of the in-mold foam molded product obtained by leaving it in a room at 23 ° C. for 4 hours. The ratio of the difference between the mold dimension and the dimension of the in-mold foam molded body with respect to the mold dimension was defined as the mold dimension shrinkage rate, and was evaluated according to the following criteria.
◎: Dimensional shrinkage ratio against mold is 4% or less ○: Dimensional shrinkage ratio against mold exceeds 4% and 7% or less ×: Dimensional shrinkage ratio against mold is larger than 7%
(実施例1〜7、比較例1)
エチレン含有率3.6重量%、MI6.0g/10分、Mw/Mnが4.7のエチレン−プロピレンランダム共重合体100重量部と、表1に示す種類・量の親水性物質、炭素数6以上30以下の脂肪酸のグリセリン部分エステル、脂肪族アルコール、有機顔料(ペリレン系有機顔料(商品名:ピグメントレッド)、又はキナクリドン系有機顔料(キナクリドンレッド))と、タルク0.1重量部を混合し、50mmφの押出機で混練(220℃)したのち、造粒し、ポリオレフィン系樹脂粒子(1.2mg/粒)を製造した。
(Examples 1-7, Comparative Example 1)
100 parts by weight of an ethylene-propylene random copolymer having an ethylene content of 3.6% by weight, MI of 6.0 g / 10 min, Mw / Mn of 4.7, a hydrophilic substance of the kind and amount shown in Table 1, carbon number Mixing glycerin partial ester of 6 to 30 fatty acids, aliphatic alcohol, organic pigment (perylene organic pigment (trade name: Pigment Red) or quinacridone organic pigment (quinacridone red)) and 0.1 part by weight of talc The mixture was kneaded (220 ° C.) with a 50 mmφ extruder and granulated to produce polyolefin resin particles (1.2 mg / grain).
300リットル耐圧容器に、水300重量部、得られたポリオレフィン系樹脂粒子100重量部、分散剤として第三リン酸カルシウム0.7重量部および分散助剤としてノルマンパラフィンスルフォン酸ソーダ0.04重量部とを仕込み、さらに、無機ガスとして炭酸ガスを10重量部仕込み、撹拌下、表1に示す温度および内圧で30分間保持したのち、耐圧容器内を炭酸ガスで前記内圧に保持しながら耐圧容器の下部に設けた3mmφオリフィスを通して水系分散物を大気圧下に放出し、一段発泡粒子をえた。そののち水で洗浄し、乾燥させた。得られた発泡粒子の発泡倍率は表1に示す通りであった。 In a 300 liter pressure-resistant container, 300 parts by weight of water, 100 parts by weight of the obtained polyolefin resin particles, 0.7 parts by weight of tribasic calcium phosphate as a dispersing agent and 0.04 parts by weight of norman paraffin sulfonate sodium as a dispersing aid. In addition, 10 parts by weight of carbon dioxide gas was added as an inorganic gas. After stirring and holding at the temperature and internal pressure shown in Table 1 for 30 minutes, the pressure vessel was held at the lower part of the pressure vessel while holding the inside pressure with carbon dioxide gas. The aqueous dispersion was discharged under atmospheric pressure through the provided 3 mmφ orifice to obtain single-stage expanded particles. After that, it was washed with water and dried. The expansion ratio of the obtained expanded particles was as shown in Table 1.
なお、親水性物質である分子量300のポリエチレングリコールをポリオレフィン樹脂100重量部に対し0.5重量部及びセル造核剤であるタルクをポリオレフィン樹脂100重量部に対し0.1重量部のみを添加した樹脂粒子を使用し、無機ガスとして窒素ガスを使用した以外は実施例1と同一条件で発泡粒子を製造し、含水率を測定したところ2.1%であった。 In addition, 0.5 parts by weight of polyethylene glycol having a molecular weight of 300, which is a hydrophilic substance, is added to 100 parts by weight of polyolefin resin, and only 0.1 part by weight of talc, which is a cell nucleating agent, is added to 100 parts by weight of polyolefin resin. Except that resin particles were used and nitrogen gas was used as the inorganic gas, foamed particles were produced under the same conditions as in Example 1, and the water content was measured and found to be 2.1%.
一段発泡粒子を耐圧容器内にて、加圧空気を含浸させて、内圧を約0.4MPa(G)にしたのち、約0.08MPa(G)の蒸気と接触させることで二段発泡させ、表1に示す発泡倍率の二段発泡粒子を得た。 The first stage expanded particles are impregnated with pressurized air in a pressure vessel, the internal pressure is set to about 0.4 MPa (G), and then contacted with steam of about 0.08 MPa (G) to form two stages, Two-stage expanded particles having an expansion ratio shown in Table 1 were obtained.
次に、得られた二段発泡粒子を1m3の耐圧容器に仕込み、0.5MPa(G)に加圧し、8時間保持して発泡粒子の内圧を0.1MPa(G)に高めたのち金型充填性評価用金型に充填し、0.3MPa(G)の水蒸気にて型内成形体を得、金型から取り出した。金型から取り出した成形体を70℃の乾燥器中で24時間乾燥、養生したのち、成形体の物性を測定した。結果を表1に示す。また、金型充填性評価用金型による成形と同様に、寸法収縮率評価用金型を用いて型内成形した。表1に示す金型充填性と寸法収縮率が得られた。 Next, the obtained two-stage expanded particles are charged into a 1 m 3 pressure vessel, pressurized to 0.5 MPa (G) and held for 8 hours to increase the internal pressure of the expanded particles to 0.1 MPa (G). A mold for mold filling property evaluation was filled, an in-mold molded body was obtained with water vapor of 0.3 MPa (G), and taken out from the mold. The molded body taken out from the mold was dried and cured in a drier at 70 ° C. for 24 hours, and then the physical properties of the molded body were measured. The results are shown in Table 1. In addition, in-mold molding was performed using a mold for evaluating dimensional shrinkage rate in the same manner as molding with a mold for mold filling evaluation. The mold filling property and dimensional shrinkage shown in Table 1 were obtained.
表1から明らかなように、本発明のポリオレフィン系樹脂発泡粒子は優れた金型充填性を有することが明らかである。参考のため表1には金型充填性評価用緩衝箱を成形した際の二段発泡粒子倍率/成形体倍率の値を示した。この値は金型充填性と相関が認められ金型充填性を示す指標と考えられる。 As is apparent from Table 1, it is clear that the polyolefin resin expanded particles of the present invention have excellent mold filling properties. For reference, Table 1 shows the values of the double-stage expanded particle magnification / molded product magnification when the buffer box for mold filling property evaluation was molded. This value is considered to be an index indicating a mold filling property, which is correlated with the mold filling property.
1 物品収納用緩衝箱
2 仕切板
1 Buffer box for storing
Claims (9)
(A)炭素数6以上30以下の脂肪酸のグリセリンエステル
(B)無機ガスとして窒素ガスを使用して発泡粒子を製造した場合、発泡粒子の含水率を0.7重量%以上にする、分子量が600以下の親水性物質 Disperse polyolefin resin particles in an aqueous dispersion medium in a pressure-resistant container, add inorganic gas, heat and press to a temperature above the softening temperature of the polyolefin resin particles, impregnate the polyolefin resin particles with a foaming agent, and foam A method for producing expanded polyolefin resin particles having an expansion ratio of 20 times or more, comprising a step of releasing the polyolefin resin particles impregnated with the agent into a pressure range lower than the internal pressure of the pressure vessel. (A) component and (B) component are contained, The manufacturing method of the polyolefin-type resin expanded particle characterized by the above-mentioned.
(A) Glycerin ester of fatty acid having 6 to 30 carbon atoms (B) When foamed particles are produced using nitrogen gas as an inorganic gas, the water content of the foamed particles is 0.7% by weight or more. 600 or less hydrophilic substance
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